1. Technical Field
The present invention relates to a piezoelectric element, a liquid ejecting head, a liquid ejecting apparatus, an ultrasonic sensor, a piezoelectric motor, and a power generating apparatus which are stably driven.
2. Related Art
There is a piezoelectric element which is configured by interposing a piezoelectric material with an electromechanical conversion function, for example, a piezoelectric body layer, which is made of a crystallized piezoelectric material, between two electrodes. Such a piezoelectric element is mounted as an actuator device in a flexural vibrating mode, for example, on a liquid ejecting head. Representative examples of the liquid ejecting head include an ink jet recording head in which a part of the pressure generation chambers communicating with nozzle openings for ejecting ink droplets is configured of a vibrating plate and ink in the pressure generation chambers is pressurized by causing the piezoelectric element to deform the vibrating plate and is ejected as ink droplets from the nozzle openings.
The piezoelectric material used in the piezoelectric body layer which configures such a piezoelectric element is required to have a high piezoelectric property. Although representative examples thereof include lead zirconate titanate (PZT) (see JP-A-2001-223404, for example), a piezoelectric element in which content of lead is suppressed has been required from a viewpoint of environmental safety. Examples of a piezoelectric material which does not contain lead include a lead-free piezoelectric material made of a BaTiO3-based oxidative product or a BiFeO3-based oxidative product with a perovskite structure (see JP-A-2009-252789, for example).
However, a lead-free piezoelectric material proposed hitherto has a lower piezoelectric property than that of a lead (Pb)-based material, and a displacement amount which is more satisfactory than that of the lead (Pb)-based material has not yet been obtained in the current situation. In order to enhance the displacement amount of such a lead-free piezoelectric material, a technique of substituting a part of elements occupying an A site of the perovskite structure or a part of elements occupying a B site thereof with an element having a different ion valence and a different ion radius has been proposed (see JP-A-2011-035385 and JP-A-2011-001257, for example).
However, it is necessary to select a site of substitution and an element of substitution in the perovskite structure, to further examine the amount of substitution and the like, and to further achieve optimization in order to achieve the displacement amount which is more satisfactory than that of the lead (Pb)-based material.
It is a matter of course that not only an ink jet recording head but also other liquid ejecting heads ejecting liquid droplets other than ink have such a problem. Moreover, piezoelectric elements used in an ultrasonic sensor, a piezoelectric motor, and a power generating apparatus also have the same problem.